Red, green and blue light emitting diodes (LED) capable of presenting high luminescence and a white light have been developing based on development of organic chemical vapor deposition and molecular beam growth of gallium nitride (GaN).
Such a light emitting diode (LED) may have advantages of good eco-friendliness because of no harmful material to the environment such as mercury (Hg), a long life span of usage and low power consumption. As a result, the light emitting diodes (LED) have been substituting for conventional light sources. Core competitive factors of such the LED may be realization of high luminescence enabled by high efficient and high output chip and packaging technology.
It is important to enhance light extraction efficiency in order to realize the high luminescence. To enhance the light extraction efficiency have been studied and developed various manners that use flip-chip, surface texturing, patterned sapphire substrate (PSS), photonic crystal technology and an anti-reflection layer structure.